President Barack Obama and David Letterman during a break in the taping of the "Late Show with David Letterman" in New York. Photo: AFP

David Letterman will retire from CBS in 2015, ending a 33-year run on TV, the longest ever for a late-night talk show host.

Letterman, 66, announced his retirement at the taping of his show today in New York, according to a statement from his company, Worldwide Pants Inc. He has been host of “The Late Show With David Letterman” on the CBS Corp. (CBS) network since 1993. From 1982, “Late Night With David Letterman” ran on NBC.

The departure completes a generational change in late-night TV. Jay Leno stepped down from “The Tonight Show” on NBC in February and was replaced by Jimmy Fallon. Leno won the job to succeed Johnny Carson over Letterman and led the ratings for most of the two decades they competed head to head.

“He is such a figure in the industry,” Bob Wright, former head of NBC, said on Bloomberg TV today. “It is not going to be simple to pick a replacement.”

Letterman informed CBS Chief Executive Officer Leslie Moonves of his decision today. Moonves had said previously his late-night host could stay as long as he wanted.

“I said ‘Leslie, it’s been great, you’ve been great, and the network has been great, but I’m retiring,’” said Letterman to a standing ovation from the studio audience, adding “we don’t have a timetable for this precisely.”

In more than 6,000 episodes, Letterman became known for off-beat comedy segments such as his top-10 lists. Leno, who often left the studio for his Jay-walking man-on-the-street skits, positioned himself as an everyman comic.

‘Sharpest interviews’

“Dave has given television audiences thousands of hours of comedic entertainment, the sharpest interviews in late night, and brilliant moments of candor and perspective around national events,” Moonves said in an e-mailed statement. “He’s also managed to keep many celebrities, politicians and executives on their toes -– including me.”

CBS, based in New York, fell 1.2 percent to $62.62 at the close in New York. It has declined 1.8 percent this year.

“The Tonight Show” on NBC remains the ratings leader and has averaged 5.21 million viewers a night since Fallon took over in February, according to Nielsen data posted at TVbythenumbers.com. That’s about double those for Letterman and ABC’s “Jimmy Kimmel Live!”

Letterman’s show was a big business for the comedian. His company produces “The Late Show,” as well as the “The Late Late Show With Craig Ferguson.”

“He makes an enormous amount of money,” Wright said. “People have no idea how much David makes from that show. Maybe that is not an issue with him anymore.”